1. Field of the Invention
The present invention relates to a photographing apparatus, a photographing method, an image processor, an image-processing method, and a program.
2. Description of Related Art
In recent years, a photographing technology called “multi-shot synthesis” (multiple-exposure synthesis) has become known in the art, in which a synthesized image is obtained by synthesizing a plurality of sequentially photographed (imaged) images in order to obtain an image that has a higher definition (higher picture quality and higher precision) than an ordinary “single-shot” image (single photographic image).
For example, in Patent Literature 1, two methods of multi-shot synthesis are disclosed: a pixel shifting method, and a picture-frame dividing method. In the pixel shifting method, a plurality of input image signals are obtained by shifting pixels by a decimal fraction of a pixel (e.g., by a ½-pixel pitch) in horizontal and vertical directions relative to the optical axis at the image sensor, and synthesizing these image signals. In the picture-frame dividing method, a single picture frame is obtained by dividing the image by a plurality of times in the vertical and horizontal directions, and a plurality of image signals are synthesized by connecting the divided areas at the divided boundaries thereof.    Patent Literature 1: Japanese Patent No. 3,193,258
Multi-shot synthesis is, by nature, assumed to have no change in the imaging conditions (the object does not move, the camera does not shake or vibrate, no obstacles occur, or no change in illumination, etc.) when a plurality of images are captured sequentially.
However, contrary to above assumption with regard to multi-shot synthesis, large changes in the imaging conditions sometimes occur (such as the object moving by a large amount, the camera shaking or vibrating by a large amount, an obstacle(s) occurring, or a large change in illumination, etc.) when a plurality of images are captured sequentially. If such a case occurs, upon the images being synthesized, an anomalous pattern occurs at an area of the picture frame where such changes have occurred that would not normally occur with normal photography, significantly deteriorating the image quality compared to an ordinary single-shot image.
FIG. 14 shows an example of a failed attempt of multi-shot synthesis. In FIG. 14, a bird has traversed the picture from the right side to the left side during sequential photography of four images. For example, if a pixel shifting method is used, since the information on the shot images that have had their pixel positions shifted is interpolated per unit of pixel pitch, a net pattern is generated along the path where the bird has traversed.